As is known, screw conveyors are used for moving pulverized material, and comprise a casing, which has a load inlet at one end, an unload outlet at the other end, and two end seals for sealing the two ends, and houses a shaft with a spiral thread rotated by actuating means.
Screw conveyors may be operated at tilt angles of 0 to 90°.
Screw conveyors of this sort are normally of considerable length, so are composed of modules, the maximum length of which is designed to prevent the thread from bending and interfering with the casing.
The joins between the thread modules are fitted with intermediate supports connected to the shaft, and which provide for structural support and for transmitting motion.
U.S. Pat. No. 7,461,902 B1, for example, describes an intermediate support for a screw extruder used in the coalmining industry, and which has a shaft fitted with a thread and rotated about an axis. The intermediate supports are equally spaced along the whole length of the shaft, and each comprise two fixed half-shells connected to the inner surface of the screw extruder casing; a fixed first ring connected to the fixed half-shells; and an inner second ring fitted to and which rotates integrally with the shaft.
Intermediate supports of this type, however, have several drawbacks.
Firstly, fitting and removing them to and from the casing and the screw shaft are fairly complicated, time-consuming, and expensive in terms of downtime.
Secondly, the intermediate supports described wear out fast, by not being perfectly isolated from the pulverized material inside the conveyor, which, mixing with the grease lubricating the supports, eventually hardens, thus damaging the supports.